In 24 persons LSD 25 blocked glycogen decomposition at the first phase of hexose-l-phosphate preventing any further cleavage down to the end products pyruvic acid and lactic acid. If the accumulation of hexose-l-phosphate in the blood is responsible for psychic symptoms, i.v. application of glucose (which is broken down directly via hexose-6-phosphate), should abolish the toxic symptoms. This seems to be the case but the number of experiments was too small to provide conclusive evidence.